吹风机外壳的模具设计与加工[三维UG]【13张CAD图纸+PDF图】
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英文原文CONCURRENT DESIGN OF PLASTICS INJECTION MOULDS Assist.Prof.Dr. A. YAYLA /Prof.Dr. Pa a YAYLAAbstract The plastic product manufacturing industry has been growing rapidly in recent years. One of the most popular processes for making plastic parts is injection moulding. The design of injection mould is critically important to product quality and efficient product processing. Mould-making companies, who wish to maintain the competitive edge, desire to shorten both design and manufacturing leading times of the by applying a systematic mould design process. The mould industry is an important support industry during the product development process, serving as an important link between the product designer and manufacturer. Product development has changed from the traditional serial process of design, followed by manufacture, to a more organized concurrent process where design and manufacture are considered at a very early stage of design. The concept of concurrent engineering (CE) is no longer new and yet it is still applicable and relevant in todays manuf acturing environment. Team working spirit, management involvement, total design process and integration of IT tools are still the essence of CE. The application of The CE process to the design of an injection process involves the simultaneous consideration of plastic part design, mould design and injection moulding machine selection, production scheduling and cost as early as possible in the design stagThis paper presents the basic structure of an injection mould design. The basis of this system arises from an analysis of the injection mould design process for mould design companies. This injection mould design system covers both the mould design process and mould knowledge management. Finally the principle of concurrent engineering process is outlined and then its principle is applied to the design of a plastic injection mould.Keywords :Plastic injection mould design, Concurrent engineering, Computer aided engineering, Moulding conditions, Plastic injection moulding, Flow simulation 1. IntroductioInjection moulds are always expensive to make, unfortunately without a mould it can not be possible ho have a moulded product. Every mould maker has his/her own approach to design a mould and there are many different ways of designing and building a mould. Surely one of the most critical parameters to be considered in the design stage of the mould is the number of cavities, methods of injection, types of runners, methods of gating, methods of ejection, capacity and features of the injection moulding machines. Mould cost, mould quality and cost of mould product are inseparable In todays completive environment, computer aided mould filling simulation packages can accurately predict the fill patterns of any part. This allows for quick simulations of gate placements and helps finding the optimal location. Engineers can perform moulding trials on the computer before the part design is completed. Process engineers can systematically predict a design and process window, and can obtain information about the cumulative effect of the process variables that influence part performance, cost, and appearance. 2. Injection MouldingInjection moulding is one of the most effective ways to bring out the best in plastics. It is universally used to make complex, finished parts, often in a single step, economically, precisely and with little waste. Mass production of plastic parts mostly utilizes moulds. The manufacturing process and involving moulds must be designed after passing through the appearance evaluation and the structure optimization of the product design. Designers face a huge number of options when they create injection-moulded components. Concurrent engineering requires an engineer to consider the manufacturing process of the designed product in the development phase. A good design of the product is unable to go to the market if its manufacturing process is impossible or too expensive. Integration of process simulation, rapid prototyping and manufacturing can reduce the risk associated with moving from CAD to CAM and further enhance the validity of the product development. 3. Importance of Computer Aided Injection Mould Design The injection moulding design task can be highly complex. Computer Aided Engineering (CAE) analysis tools provide enormous advantages of enabling design engineers to consider virtually and part, mould and injection parameters without the real use of any manufacturing and time. The possibility of trying alternative designs or concepts on the computer screen gives the engineers the opportunity to eliminate potential problems before beginning the real production. Moreover, in virtual environment, designers can quickly and easily asses the sensitivity of specific moulding parameters on the quality and manufacturability of the final product. All theseCAE tools enable all these analysis to be completed in a meter of days or even hours, rather than weeks or months needed for the real experimental trial and error cycles. As CAE is used in the early design of part, mould and moulding parameters, the cost savings are substantial not only because of best functioning part and time savings but also the shortens the time needed to launch the product to the market. The need to meet set tolerances of plastic part ties in to all aspects of the moulding process, including part size and shape, resin chemical structure, the fillers used, mould cavity layout, gating, mould cooling and the release mechanisms used. Given this complexity, designers often use computer design tools, such as finite element analysis (FEA) and mould filling analysis (MFA), to reduce development time and cost. FEA determines strain, stress and deflection in a part by dividing the structure into small elements where these parameters can be well defined. MFA evaluates gate position and size to optimize resin flow. It also defines placement of weld lines, areas of excessive stress, and how wall and rib thickness affect flow. Other finite element design tools include mould cooling analysis for temperature distribution, and cycle time and shrinkage analysis for dimensional control and prediction of frozen stress and warpage. The CAE analysis of compression moulded parts is shown in Figure 1. The analysis cycle starts with the creation of a CAD model and a finite element mesh of the mould cavity. After the injection conditions are specified, mould filling, fiber orientation, curing and thermal history, shrinkage and warpage can be simulated. The material properties calculated by the simulation can be used to model the structural behaviour of the part. If required, part design, gate location and processing conditions can be modified in the computer until an acceptable part is obtained. After the analysis is finished an optimized part can be produced with reduced weldline (known also knitline), optimized strength, controlled temperatures and curing, minimized shrinkage and warpage. Machining of the moulds was formerly done manually, with a toolmaker checking each cut. This process became more automated with the growth and widespread use of computer numerically controlled or CNC machining centres. Setup time has also been significantly reduced through the use of special software capable of generating cutter paths directly from a CAD data file. Spindle speeds as high as 100,000 rpm provide further advances in high speed machining. Cutting materials have demonstrated phenomenal performance without the use of any cutting/coolant fluid whatsoever. As a result, the process of machining complex cores and cavities has been accelerated. It is good news that the time it takes to generate a mould is constantly being reduced. The bad news, on the other hand, is that even with all these advances, designing and manufacturing of the mould can still take a long time and can be extremely expensive. Figure 1 CAE analysis of injection moulded parts Many company executives now realize how vital it is to deploy new products to market rapidly. New products are the key to corporate prosperity. They drive corporate revenues, market shares, bottom lines and share prices. A company able to launch good quality products with reasonable prices ahead of their competition not only realizes 100% of the market before rival products arrive but also tends to maintain a dominant position for a few years even after competitive products have finally been announced (Smith, 1991). For most products, these two advantages are dramatic. Rapid product development is now a key aspect of competitive success. Figure 2 shows that only 37% of the product mix from the average industrial or electronics company is less than 5 years old. For companies in the top quartile, the number increases to 1525%. For world-class firms, it is 6080% (Thompson, 1996). The best companies continuously develop new products. At Hewlett-Packard, over 80% of the profits result from products less than 2 years old! (Neel, 1997) Figure 2. Importance of new product (Jacobs, 2000) With the advances in computer technology and artificial intelligence, efforts have been directed to reduce the cost and lead time in the design and manufacture of an injection mould. Injection mould design has been the main area of interest since it is a complex process involving several sub-designs related to various components of the mould, each requiring expert knowledge and experience. Lee et. al. (1997) proposed a systematic methodology and knowledge base for injection mould design in a concurrent engineering environment. 4. Concurrent Engineering in Mould Design Concurrent Engineering (CE) is a systematic approach to integrated product development process. It represents team values of co-operation, trust and sharing in such a manner that decision making is by consensus, involving all per spectives in parallel, from the very beginning of the product life-cycle (Evans, 1998). Essentially, CE provides a collaborative, co-operative, collective and simultaneous engineering working environment. A concurrent engineering approach is based on five key elements: 1. process 2. multidisciplinary team 3. integrated design model 4. facility 5. software infrastructure Figure 3 Methodologies in plastic injection mould design, a) Serial engineering b) Concurrent engineering In the plastics and mould industry, CE is very important due to the high cost tooling and long lead times. Typically, CE is utilized by manufacturing prototype tooling early in the design phase to analyze and adjust the design. Production tooling is manufactured as the final step. The manufacturing process and involving moulds must be designed after passing through the appearance evaluation and the structure optimization of the product design. CE requires an engineer to consider the manufacturing process of the designed product in the development phase. A good design of the product is unable to go to the market if its manufacturing process is impossible. Integration of process simulation and rapid prototyping and manufacturing can reduce the risk associated with moving from CAD to CAM and further enhance the validity of the product developmentFor years, designers have been restricted in what they can produce as they generally have to design for manufacture (DFM) that is, adjust their design intent to enable the component (or assembly) to be manufactured using a particular process or processes. In addition, if a mould is used to produce an item, there are therefore automatically inherent restrictions to the design imposed at the very beginning. Taking injection moulding as an example, in order to process a component successfully, at a minimum, the following design elements need to be taken into account: 1. . geometry; . draft angles, . Non re-entrants shapes, . near constant wall thickness, . complexity, . split line location, and . surface finish, 2. material choice; 3. rationalisation of components (reducing assemblies); 4. cost. In injection moulding, the manufacture of the mould to produce the injection-moulded components is usually the longest part of the product development process. When utilising rapid modelling, the CAD takes the longer time and therefore becomes the bottleneck. The process design and injection moulding of plastics involves rather complicated and time consuming activities including part design, mould design, injection moulding machine selection, production scheduling, tooling and cost estimation. Traditionally all these activities are done by part designers and mould making personnel in a sequential manner after completing injection moulded plastic part design. Obviously these sequential stages could lead to long product development time. However with the implementation of concurrent engineering process in the all parameters effecting product design, mould design, machine selection, production scheduling, tooling and processing cost are considered as early as possible in the design of the plastic part. When used effectively, CAE methods provide enormous cost and time savings for the part design and manufacturing. These tools allow engineers to virtually test how the part will be processed and how it performs during its normal operating life. The material supplier, designer, moulder and manufacturer should apply these tools concurrently early in the design stage of the plastic parts in order to exploit the cost benefit of CAE. CAE makes it possible to replace traditional, sequential decision-making procedures with a concurrent design process, in which all parties can interact and share information, Figure 3. For plastic injection moulding, CAE and related design data provide an integrated environment that facilitates concurrent engineering for the design and manufacture of the part and mould, as well as material selection and simulation of optimal process control parameters. Qualitative expense comparison associated with the part design changes is shown in Figure 4 , showing the fact that when design changes are done at an early stages on the computer screen, the cost associated with is an order of 10.000 times lower than that if the part is in production. These modifications in plastic parts could arise fr om mould modifications, such as gate location, thickness changes, production delays, quality costs, machine setup times, or design change in plastic parts. Figure 4 Cost of design changes during part product development cycle (Rios et.al, 2001)At the early design stage, part designers and moulders have to finalise part design based on their experiences with similar parts. However as the parts become more complex, it gets rather difficult to predict processing and part performance without the use of CAE tools. Thus for even relatively complex parts, the use of CAE tools to prevent the late and expensive design changesand problems that can arise during and after injection. For the successful implementation of concurrent engineering, there must be buy-in from everyone involved. 5.Case Study Figure 5 shows the initial CAD design of plastics part used for the sprinkler irrigation hydrant leg. One of the essential features of the part is that the part has to remain flat after injection; any warping during the injection causes operating problems. Another important feature the plastic part has to have is a high bending stiffness. A number of feeders in different orientation were added to the part as shown in Figure 5b. These feeders should be designed in a way that it has to contribute the weight of the part as minimum as possible. Before the design of the mould, the flow analysis of the plastic part was carried out with Moldflow software to enable the selection of the best gate location Figure 6a. The figure indicates that the best point for the gate location is the middle feeder at the centre of the part. As the distortion and warpage of the part after injection was vital from the functionality point of view and it has to be kept at a minimum level, the same software was also utilised to yiled the warpage analysis. Figure 5 b shows the results implying the fact that the warpage well after injection remains within the predefined dimensional tolerances. 6.Conclusions In the plastic injection moulding, the CAD model of the plastic part obtained from commercial 3D programs could be used for the part performance and injection process analyses. With the aid of CEA technology and the use of concurrent engineering methodology, not only the injection mould can be designed and manufactured in a very short of period of time with a minimised cost but also all potential problems which may arise from part design, mould design and processing parameters could be eliminated at the very beginning of the mould design. These two tools help part designers and mould makers to develop a good product with a better delivery and faster tooling with less time and money. Referenc1.Smith P, Reinertsen D, The time-to-market race, In: Developing Products in Half the Time. New York, Van Nostrand Reinhold, pp. 313, 19912.Thompson J, The total product development organization. Proceedings of the Second AsiaPacific Rapid Product Development Conference, Brisbane, 1996 3.Neel R, Dont stop after the prototype, Seventh International Conference on Rapid Prototyping, San Francisco, 1997 4.Jacobs PF, “Chapter 3: Rapid Product Development” in Rapid Tooling: Technologies and Industrial Applications , Ed. Peter D. Hilton; Paul F. Jacobs, Marcel Decker, 20005.Lee R-S, Chen, Y-M, and Lee, C-Z, “Development of a concurrent mould design system: a knowledge based approach”, Computer Integrated Manufacturing Systems, 10(4), 287-307, 1997 6.Evans B., “Simultaneous Engineering”, Mechanical Engineering , Vol.110, No.2, pp.38-39, 1998 7.Rios A, Gramann, PJ and Davis B, “Computer Aided Engineering in Compression Molding”, Composites Fabricators Association Annual Conference , Tampa Bay, 2001 中文译文塑料注射模具的并行设计摘要 塑料产品制造业已在近几年迅速增长。用于制造塑料部件的最流行的过程之一是注塑。注塑模具的设计是非常重要的产品质量和高效的产品加工。 模具制造公司，谁愿意以保持竞争优势，缩短应用系统的模具设计过程中，设计和制造领先时代的欲望。模具行业在产品开发过程中的重要支撑产业，作为产品的设计者和制造商之间的一个重要环节。从产品的发展，改变了传统的串行设计过程中，其次是制造，一个更有组织的并发设计和制造过程中被认为是在一个非常早期的设计阶段。并行工程（CE）的概念已不再是新鲜事，但它仍然是适用的，在今天的化学品制造acturing环境相关。团队合作精神，管理人员的参与，整个设计过程和集成的IT工具仍然是CE的本质。同时考虑应用的CE程序设计的一个注入进程涉及的塑料零件设计，模具设计和注塑机选择，生产调度和成本尽早在设计雄鹿 本文介绍了注塑模具设计的基本结构。这个系统的基础上产生的注塑模具设计过程的分析，模具设计公司。注塑模具设计系统涵盖了模具设计工艺和模具知识管理。最后的原则的并发工程过程的概述，然后被施加到其原理的塑料注射模具的设计。关键词：注塑模具的设计，并行工程，计算机辅助工程，成型条件，注塑成型，流程模拟1.导论 注塑模具往往成本很大，不幸的是没有的模具，它不能是可能浩有一个模制产品。每一个模具制造商都有他/她自己的方式来设计模具，模具的设计和建设一个有许多不同的方式。当然，模具的设计阶段，要考虑的最重要的参数之一是空腔，注射方法，跑步者的类型的，选通的方法，喷射，容量和特性的注塑机的方法的数量。模具成本，模具的模具产品的质量和成本是分不开的。 在今天的环境，计算机辅助模具填充仿真工具包，可以准确地预测任何部分的填充图案。这可以快速模拟的门安置，并帮助找到最佳的位置。以前的部分设计完成后，工程师可以在电脑上进行成型试验。工艺工程师可以系统地预测设计和工艺窗口，可以获取信息的过程变量影响性能，成本和外观的累积效应。2.注塑成型 注塑成型是最好的塑料带出最有效的方法之一。这是普遍使用的，往往是在一个单一的步骤，使复杂，成品零件经济，精确和废物少。大规模生产的塑料部件大多采用的模具。后通过的外观评价及结构优化的产品设计，制造过程中，涉及模具的设计必须。设计人员面临的注塑成型部件的选择，当他们创建一个庞大的数字。并行工程要求工程师在开发阶段考虑制造过程的设计的产品。一个好的设计的产品是不能去的市场，如果其生产过程中是不可能的，或过于昂贵。与从CAD到CAM过程的仿真，快速原型制造的集成可以降低风险，进一步提升产品开发的有效性。3.计算机辅助注塑模具设计的重要性 注塑模具设计任务可以是非常复杂的。计算机辅助工程（CAE）分析工具使设计工程师提供了巨大的优势，几乎和零件，模具及注塑参数没有真正的使用任何制造和时间的考虑。尝试另一种设计或概念在计算机屏幕上的可能性给出了工程师的机会，以消除潜在的问题，然后再开始真正的生产。此外，在虚拟环境中，设计人员可以快速，方便地评估特定的成型参数对最终产品的质量和可制造性的灵敏度。所有theseCAE工具，使所有这些分析，在一米的几天甚至几个小时内完成，而不是几周或几个月需要对实际的试验和错误周期。由于采用的是早期设计的零件，模具和成型工艺参数CAE不仅是因为最佳的功能的一部分，节省时间，也缩短了所需的时间向市场推出的产品，节约成本是巨大的。 需要设定的公差，以满足的塑料部分关系到成型过程中的各个方面，包括零件的尺寸和形状，树脂的化学结构，使用的填料，模腔布局，浇注，模具冷却和释放机制。鉴于这种复杂性，设计人员经常使用电脑的设计工具，如有限元分析（FEA）和模流分析（MFA），以减少开发时间和成本。有限元分析确定应变，应力和偏转通过划分成小的元素，这些参数可以很好地定义的结构的一部分中。 MFA评估浇口位置和大小以优化树脂流动。它还定义的焊接线，过度紧张的地区，壁和肋骨厚度如何影响流量的位置。其他有限元设计工具，包括模具的冷却温度分布，分析和三维控制和预测分析的冻结应力和翘曲的周期时间和收缩。图1中所示的压缩模制零件的CAE分析。分析周期开始与创建的CAD模型和有限元网格的模腔。注射后的条件规定，可以模拟模具填充，纤维取向，固化和热历史，收缩和翘曲。通过模拟计算出的材料性能，可以使用的部分的结构的行为进行建模。如果需要的话，部件设计，浇口位置和加工条件可以在计算机中进行修改，直到获得一个可以接受的部分。分析完成后，就可以生产出一个优化的部分减少熔合线（又称knitline），优化的强度，控制温度和固化，最小化收缩和翘曲。模具加工的前身是手工完成，检查每个切与工具制造商。这个过程变得更加自动化的发展和广泛使用的计算机数控CNC加工中心。安装时间也显着减少了通过使用特殊的软件，能够直接从CAD数据文件生成的刀具路径。高达10万转的主轴转速提供高速加工的进一步发展。切削材料表现出惊人的性能，而无需使用任何任何切割/冷却流体。其结果是，已加速加工复杂的过程中，芯和模腔。 不断地被降低，所花费的时间，以生成的模具，这是好消息。 ，另一方面，坏消息是，即使所有这些进步，设计和制造的模具还需要很长的时间，可能会非常昂贵。CAE分析图1的注射成型部件 现在很多公司高管意识到它是多么的重要部署新产品迅速推向市场。新产品是企业繁荣的关键。他们带动公司收入，市场份额，底线和股价。一个公司能够推出优质的产品，合理的价格，领先的竞争不仅实现了100的市场份额，竞争对手的产品之前到达，但也往往保持优势地位，竞争力的产品后，终于被宣布为几年（史密斯， 1991）。对于大多数产品，这两方面的优势是显着的。快速的产品开发竞争中获得成功的一个重要方面。从图2可以看出，只有3-7的平均工业电子公司的产品组合是小于5岁。对于公司的前四分之一，数增加至15-25。对于世界级的公司，它
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